This invention relates broadly to the art of continuous and semicontinuous metal casting systems, and more particularly, to such systems wherein an electromagnetic inductor serves to shape molten metal prior to solidification thereof.
Prior-art patents disclosing electromagnetic casting systems of the type to which this invention relates include U.S. Pat. Nos. 3,467,166 to Getselev et al., 3,605,865, 3,702,155 and 3,773,101 to Getselev, 3,735,799 to Karlson, and 3,985,179 and 4,004,631 to Goodrich et al. as well as to U.S. Pat. application Ser. No. 728,797 filed Oct. 1, 1976 by Carson et al.
These prior-art patents describe systems for continuously and semicontinuously electromagnetically casting wherein molten metal is introduced at a controlled rate onto a movable bottom block, or pan, located within a loop-shaped electrical inductor. The bottom block is lowered at a controlled rate with metal flow being controlled in accordance with this rate to form an ingot. The molten metal so introduced is confined laterally inside the inductor by an electromagnetic field generated by an alternating current in the inductor. The molten metal is thus formed into a shape in a horizontal plane similar to, but smaller than, the inductor. The emerging bottom block and ingot are subjected to rapid cooling by the application of a coolant, such as water, to solidify the ingot into this shape.
In most of these type systems there is a tapered electromagnetic shield or screen located inside the inductor arranged coaxially therewith made of a non-magnetic, but electrically conductive, metal, such as stainless steel. The shield, because of its taper, serves to attenuate the magnetic field of the inductor upwardly, thereby lessening the electromagnetic forces restraining the ingot at the top as opposed to those at the lower edge of the shield. The advantages of such a shield are more fully described in U.S. Pat. No. 3,605,865 to Getselev, and the information in that patent is incorporated by reference herein.
In practice, these shields get quite hot during operation because of their close proximity to molten metal forming the ingot and because they absorb so much energy from the electromagnetic field of the inductor. Thus, the shields must often be cooled by spraying coolant onto them. This heating and cooling of the shields often causes warping thereof to create nonuniformity in the attenuation of the electromagnetic field and to vary the impingement of coolant falling from such warped shields onto the ingots being cast. It is therefore an object of this invention to provide mounting supports for continuous-casting, electromagnetic shields which help prevent the warping thereof.
The shields must be relatively rigid so that they can be positioned uniformly between an ingot being cast and the inductor. Thus, it is an object of this invention to provide a mounting for a shield of an electromagnetic casting apparatus which holds the shield sturdily and rigidly to maintain it in a proper shape and position.
It is a further object of this invention to provide such a shield for an electromagnetic casting system which is easy to mount.
As is noted above, the coolant which is sprayed onto the shield to cool it is often a problem in that it falls onto ingots being cast in a nonuniform manner. Further, if this coolant is dropped straight downwardly without impinging on the ingot it sometimes interferes with coolant being sprayed independently onto the ingot. Thus, it is another object of this invention to provide a system for cooling a shield with a coolant which provides uniform coolant flow onto ingots being cast and which does not interfere with independently sprayed coolant.
It is also an object of this invention to provide a shield which is economical and uncomplicated to manufacture.